The present invention refers to a dispensing device of ashing agents for a household washing machine, in particular a dishwasher, as described in the preamble of the annexed claim 1.
As known, washing machines are usually fitted with a dispensing device of washing agents, namely powder and/or liquid detergents and additives; typically, the latter consist of softening substances for laundry washing machines and rinsing aids for dishwashing machines.
In the instance of the dishwashers, the washing agents dispenser usually comprises a body made in plastic material, partially built-in in one of the vertical surfaces delimiting the washing tub of the machine; in most cases, this vertical wall is the dishwasher inner door, i.e. the side of the machine front loading door facing inside the washing tub.
In its front area, the above body delimits a space for containing a washing agent, usually powder or in the form of a tablet, with a tilting or sliding cover; the opening of this cover is appropriately controlled by a machine programmer or timer.
A tank is provided inside the dispenser body for containing a second washing agent of the liquid type, typically a rinsing aid; in general, this tank has a capacity for containing a sufficient amount of liquid agent for several washing cycles: so that the machine user has only to fill the tank periodically, through a proper plug.
A small chamber inside the dispenser is associated with the above tank for dosing the amount of rinsing aid to be dispensed during a washing cycle; to this purpose the dosing system of the rinsing aid uses the opening-closing movement of the machine door, i.e. horizontal in its open position and vertical in its closed position, for dispensing a portion of rinsing aid from the tank to the dosing chamber; during machine operation, the programmer operates an actuator to release a discharge outlet in line with the dosing chamber, so that the amount of rinsing aid can flow from the latter into the washing tub of the dishwasher.
As described above, according to the technique previously known presuppose that the dispenser has to be fastened to the dishwasher door, in order to utilize its opening-closing movement for dosing the rinsing aid required for executing a wash cycle; therefore, for this reason, application of these dispensers is restricted to washing machines with a tilting door around a horizontal axis.
However, in some known washing machines the loading door is not tilting but it is linearly sliding on appropriate guides; with reference to a twin-basket dishwashing machine, reference can be made for instance to the solution described in FR-A-2.674.426; vice-versa, according to other known solutions, the dishwasher has only one basket designed like a sliding drawer for containing the crockery to be washed, whose front wall is actually representing the machine door.
Also in these machines, the washing agents dispenser is fastened to the machine door or anyway to a wall or vertical surface delimiting the washing tub; as a result, the dispenser is always laying on the same resting plane, independently from the door open-closed condition.
Therefore, the dispensers applied to these machines have to be equipped with a proper electric pump, either a vibration or peristaltic pump, in order to perform the dosing and dispensing of the liquid washing agent; however, these pumps are relatively expensive, space requiring and difficult to control; moreover, these pumps may go out of calibration or become defective with time, also considering a possible corrosive capacity of certain liquid washing agents.
On the contrary, other known solutions provide a special hydraulic circuit, being able to convey water inside the device for dispensing the liquid washing agent and convey it into the machine washing tub; however, also these solutions are complicated, expensive and critical, considering that such an hydraulic circuit should be partially housed within the machine door.